This invention relates to cellular polyurethane products and, more particularly, to hydrophilic, flexible, open cell polyurethane-poly(n-vinyl lactam) interpolymer foams and various dental and biomedical products, e.g., laparotomy sponges, bandages and medicament carriers and the like, fabricated therefrom.
U.S. Pat. Nos. 2,726,219, 2,901,445, 3,694,301, 3,890,254, 3,903,232, 4,127,516, 4,137,200 and 4,160,076, among others, show that it is old to prepare a hydrophilic polyurethane foam employing a one-shot or, more commonly, a prepolymer, procedure using water as blowing agent. Each of these prior patents describes the preparation of polyurethane polymers and prepolymers based on polyalkylene ether glycols and organic diisocyanates. Several of the disclosures further describe the use of surface active agents to provide foams having improved cell structure.
U.S. Pat. No. 2,965,584 discloses the preparation of a foamed hydrophilic polyurethane employing a pyrrolidone such as vinylpyrrolidone as catalyst. There is no hint whatever in this patent of forming a foamed polyurethane-polyvinylpyrrolidone interpolymer. While U.S. Pat. Nos. 4,100,309 and 4,119,094 disclose solid polyurethane-polyvinylpyrrolidone interpolymers, there is no suggestion in these patents of preparing foams from such interpolymers.
As shown in U.S. Pat. Nos. 3,961,629, 3,972,328, 3,975,567, 3,978,266, 3,978,855, 4,127,124, 4,202,880, 4,235,988 and 4,339,550, the use of hydrophilic, flexible, open cell polyurethane foams for a variety of medical and surgical applications, including surgical dressings, drug carriers, and the like, is well known. However, there is no suggestion in these patents of using a foamed polyurethane-poly(N-vinyl lactam) interpolymer for any of the medical/surgical applications disclosed therein.